Tool changer for a machine tool

Abstract

A tool changer for machine tools having at least two tong-shaped grippers, the legs of which are formed for engaging with the ring groove at a broader end of a tool taper. The grippers are symmetrically mounted about the central axis of a carrier and are rotatable around the central axis with their legs pointing outward. The carrier is mounted on a support structure that has a drive for moving the carrier. In order to enable an earlier release of the tool taper from the collet chuck in the work spindle, and thus faster tool changes, at least one leg of the grippers is extended to form a protruding holding finger.

1. A tool changer for a machine tool, said tool changer comprising:
 at least two tong-shaped grippers, said grippers comprising at least two legs configured engagement with a ring groove at a broad end of the taper of a tool, at least one of said legs being extended and being substantially longer than the other said leg to form a protruding holding finger to prevent the tool from dislodgement from the machine tool when released by the machine tool and prior to secure engagement of the tool by the tool changer; 
 a carrier rotatable about a central axis, said carrier having said grippers mounted symmetrically thereon on the opposing sides of the central axis with the legs pointing outward; and 
 a support structure for the carrier, said support structure comprising a drive for moving the carrier in an axis parallel to the axis of a work spindle. 
 
   
   
     2. The tool changer according to  claim 1 , wherein the work spindle can travel in a horizontal direction across the longitudinal axis of the spindle for lateral engagement of the gripper. 
   
   
     3. The tool changer according to  claim 1 , wherein the protruding holding finger is curved at least at its radial inner area and further comprises a curved holding and guiding bracket. 
   
   
     4. The tool changer according to  claim 1 , wherein one leg of the grippers curves gradually into a curved holding segment carrying a guiding bracket on its curved surface. 
   
   
     5. The tool changer according to  claim 4 , wherein the holding segment of the gripper is mounted on the carrier. 
   
   
     6. The tool changer according to  claim 5 , wherein the two legs of the grippers are rigid and a securing holder is provided at least on one leg. 
   
   
     7. The tool changer according to  claim 6 , wherein the securing holder comprises a projecting spring-biased holding member. 
   
   
     8. The tool changer according to  claim 7 , wherein four grippers are arranged in pairs diametrically opposed on the carrier. 
   
   
     9. The tool changer according to  claim 1 , wherein said legs of said grippers have an open position and a holding position, at least one of said at least two legs is movable to the open position and is lockable in the holding position for securely holding the tool. 
   
   
     10. A method for changing a tool out of a machine tool, the method comprising: rotating a rotatable tool changer into position to engage a spent tool in the machine tool, the tool changer having at least two tong-shaped grippers, each comprised of at least two legs, at least one of said legs being substantially longer than the other said leg;
 holding the tool in place in the machine tool by means of the longer leg after release of the tool by the machine tool and prior to secure engagement of the tool by the tool changer; 
 securely engaging the tool by the tool changer; 
 locking the at least two legs onto the tool; and 
 removing the tool from the machine tool.